During Blade Idle, you can equip up to a maximum of 5 skills depending on your level. Each piece of content in the game has a different goal. Though you are simply slaying monsters, you have to consider the distance from monsters, cooldowns between skills, and the amount of damage you are taking.
For example, Phantom Blade is a high-damage skill, but you can take a lot of damage from monsters while using it, so it is not always an ideal option for a dungeon that requires you to survive for a decent amount of time.
After speaking and confirming with the Blade Idle Community, I have been able to list the best skills to use in Blade Idle for each type of content.
Clearing Stages
Space Field, Phantom Blade, Rain of Sword, Piercing Blade, Summon Tornado
Farming Stages (Offline)
Space Field, Reckless Blast, Chain Dash, Charge Boom, Summon Tornado.
Enchant Stone Dungeon
If your Chain Dash is level 4 or above, then use this build:
Space Field, Rain of Sword, Chain Dash, Piercing Blade, Summon Tornado.
Otherwise use the following build:
Space Field, Rain of Sword, Phantom Blade, Piercing Blade, Summon Tornado
Pet Dungeon
Space Field, Rain of Sword, Phantom Blade, Piercing Blade, Summon Tornado
Relic Dungeon
Space Field, Reckless Blast, Chain Dash, Charge Boom, Summon Tornado
Emblem Dungeon
Space Field, Rain of Sword, Phantom Blade, Piercing Blade, Summon Tornado
Insignia Dungeon
Space Field, Rain of Sword, Phantom Blade, Piercing Blade, Summon Tornado
Raid Dungeon
Summon Tornado, Space Field, Phantom Blade, Rain of Swords & Piercing Blade
